To keep tabs on how our bodies are working, doctors need to measure physiological parameters like blood pressure, body temperature, and pulse. However, there is often a mismatch in physical dimensions and properties between electronic instruments and the human body, which limits the quality and reliability of such measurements. Overcoming this technological barrier, Kim and colleagues have introduced a novel electronic device that closely matches the mechanical properties of human skin to measure physiological signals from the heart, brain, and muscle.

Different from traditional electronic devices, this new epidermal device integrates all of its miniature components into one flexible polyester membrane. Thanks to van der Waals forces, the super-thin device can easily adhere and conform to the skin by simply rubbing water at the interface. The membrane’s mechanical properties, such as elasticity, are very similar to those of human skin, and all of the wiring between electronic components uses a “serpentine” design, so the device remains attached, even when the skin bends or stretches. The authors built one prototype, which was about 2 cm2 and contained all essential electronic components for sensing temperature, strain, and electrophysiological signals; as well as amplifiers, wireless communication antenna and coils, and power receiving coils. Using this prototype on one human volunteer, Kim et al. recorded signals from the brain and heart as well as from the skeletal muscles in the throat, demonstrating recognition of four words: “up,” “down,” “left,” and “right.” Similar flexible electronic designs could be adapted to make new devices that can mechanically conform to a specific organ or tissue of interest, which will greatly advance physiological monitoring in both in the the clinic and in daily life.